A. I. Kozlov

Focal plane arrays based on HgCdTe epitaxial layers MBE-grown on GaAs substrates

Heterostructures HgCdTe/CdTe/GaAs grown by molecular beam epitaxy were used for LWIR FPA fabrication. The technology was developed and 32 by 32 and 128 by 128 photodiode arrays with indium bumps of 15 micrometer height in each pixel were fabricated. Mean NEP is 1.7 by 10-13 W/Hz1/2 and 1.1 by 10-14 W/Hz1/2 for 128 by 128 photodiode arrays with (lambda) c value of 10.4 micrometer and 5.2 micrometer correspondently. The technology of hybrid assembling with continuous control of cold welding on the measuring stand was demonstrated on the example of 32 by 32 LWIR FPA. Mean NEP value of 5.4 by 10-14 W/Hz1/2 with (lambda) c equals 10.6 micrometer at 80 K operation were obtained. using an infrared camera system the infrared image was successfully demonstrated. The NETD value of 0.077 K was obtained under 293 K background condition.

Analysis of design principles of silicon multiplexer circuits for multielement infrared focal plane arrays

Design principles of silicon multiplexers for linear and matrix infrared (IR) focal plane arrays (FPAs) are considered. Silicon multiplexers intended for operation with multielement mercury-cadmium-tellurium (MCT) photodiode detectors, with multielement photoresistor detectors based on multilayer structures with quantum wells, and with other types of photodetectors sensitive to radiation in the IR ranges from 3 to 5 and from 8 to 16 µm, are discussed. The type and size range of the multiplexers includes 19 models that differ in frame sizes, input circuits, charge capacity, and cell pitch. Around the designed multiplexers, hybrid and monolithic FPAs of various formats for medium and far IR ranges with a rather high temperature resolution (< 0.02 K) have been developed.

Manufacturing-oriented developments of silicon multiplexers for multielement IR photodetectors

The architecture of silicon multiplexers for multielement IR photodetectors is considered. A review is given of industrially oriented developments of linear (1 × 32, 1 × 288, 1 × 576) and matrix (32 × 32, 128 × 128, 160 × 128, 320 × 256) silicon multiplexers for mid- and far-IR photodetectors based on cadmium-mercury-tellurium, lead-tin-tellurium, and multilayer structures with quantum wells. An analysis is made of the temperature resolution of matrix IR photodetectors based on multiplexers with row and frame integration of photo signals using micrometer to deep submicron CMOS technologies. Typical parameters of the multiplexer and some of the infrared photodetectors designed at the Rzhanov Institute of Semiconductor Physics, SB RAS are given.

A series of silicon multiplexers for HgCdTe photodiodes of the 8-16-μm spectral range

This paper presents the results of the development of linear (1×288, 1×576) and two-dimensional (128×128, 320×256) silicon multiplexer arrays for HgCdTe photodiodes of the 8-16μm spectral range. Typical parameters of the multiplexers are given, along with the characteristics of long-wavelength hybrid IR photodetectors created at the Institute of Semiconductor Physics of the Siberian Section of the Russian Academy of Sciences.

320 × 256 Silicon multiplexers for IR focal plane arrays based on MCT diodes

Principles of designing and functioning the 320 × 256 frame and row integration matrix multiplexers are considered. The temperature resolution of the MCT IR FPA and the designed multiplexers is analyzed.

Technological limitations in readout integrated circuits for infrared focal plane arrays based on quantum-well infrared photodetectors

This paper presents the physical and technical principles of readout integrated circuit (ROIC) for reading and preprocessing focal plane array signals in the infrared spectral range 8–14 μm. The noise equivalent temperature difference of long-wavelength infrared focal plane arrays based on ROIC with frame integration of signals of multilayer quantum well structures is evaluated. The influence of technological limitations in silicon readout circuits for photo signals on the performance of IR focal plane arrays is analyze for a wide range of parameters of QWIP -based focal plane arrays and CMOS technology design rules.

Investigating processes for forming an infrared CdHgTe-based photodetector in a monolithic version

This paper discusses the results of investigations of processes for forming monolithic integrated cadmium-mercury telluride (CdHgTe)-based IR arrays and their parameters. The processes for growing CdHgTe heteroepitaxial layers (HELs) by molecular-beam epitaxy (MBE) in the cells of a silicon multiplexer have been studied, as well as for forming an n-p junction and contact compounds. For the selective growth of CdHgTe MBE HELs, regimes have been determined for preparing a silicon surface in dielectric windows with dimensions from 30×30to100×100μm. Selective layers of CdHgTe (8μm)/CdTe(5-7μm)/ZnTe(0.02μm) have been grown on Si (310). Ion implantation of boron into selective p-type layers has been used to form n-p junctions. Measurements showed that the parameter R0A is 1.25×105Ωcm2 for the spectral range 3-5μm. A monolithic linear array of format 1×32, based on a CdHgTe MBE HEL, has been fabricated by growth in the cells of a silicon multiplexer.

Silicon multiplexers for 1 × 576 HgCdTe IR focal-plane arrays

Two versions of silicon 1D multiplexer for 1 × 576 IR focal-plane arrays are designed, fabricated, and tested. The version LM-1 employs a direct-injection input circuit; the version LM-2 contains a buffered direct-injection circuit. They are intended for use with HgCdTe n+-p photodiodes operating in the wavelength ranges 8–14 and 3–5 μm, the minimum reverse diode resistance being 200 kΩ. The multiplexers ensure high uniformity of photodiode bias voltage; they are provided with a switched storage capacitance, which allows operation at different signal, background, and dark currents. Clocked at 3.5 MHz, they have an integration time of 40 μs and can read out 25 full-size (768 × 576) frames per second.

The 4×288 linear FPA on the heteroepitaxial Hg 1-x Cd x Te base

x4×288 heteroepitaxial mercury-cadmium telluride (MCT) linear arrays for long wavelength infrared (LWIR) applications with 28×25 micron diodes and charge coupled devices (CCD) silicon readouts were designed, manufactured and tested. MCT heteroepitaxial layers were grown by MBE technology on (013) GaAs substrates with CdZnTe buffer layers and have cutoff wavelength λco ≈ 11.8 μm at T = 78 K. To decrease the surface influence of the carriers recombination processes the layers with composition changes and its increase both toward the surface and HgCdTe/CdZnTe boundary were grown. Silicon read-outs with CCD multiplexers with input direct injection circuits were designed, manufactured and tested. The testing procedure to qualify read-out integrated circuits (ROICs) on wafer level at T = 300 K was worked out. The silicon read-outs for 4×288 arrays, with skimming and partitioning functions included were manufactured by n-channel MOS technology with buried or surface channel CCD register. Designed CCD readouts are driven with four- or two-phase clock pulses. The HgCdTe arrays and Si CCD readouts were hybridized by cold welding indium bumps technology. With skimming mode used for 4×288 MCT n-p-junctions, the detectivity was about (formula available in paper) for background temperature Tb = 295 K.

Optimizing the parameters of a system consisting of a photosensitive IR element based on multilayer structures with quantum wells and a silicon photoelectric multiplexer

This paper discusses the design and process principles involved in optimizing the noise-equivalent temperature difference of photodetectors based on multilayer structures with quantum wells in wide ranges of the structural and process limitations of silicon multiplexers, CMOS-technology design norms, and the parameters of photosensitive elements for the long-wavelength IR spectral region.